The present invention pertains to accumulating conveyors, and, in particular, to an accumulating conveyor intended for heavy duty use, as for conveying pallets.
Accumulating conveyors are known in the art. They provide more control over the flow of material than normal conveyors. Accumulating conveyors are typically divided into zones of belts or rollers and include some type of control means whereby zones are driven or remain idle depending upon the location of articles on the conveyor. In a standard conveyor in which the whole conveyor is driven at a fixed rate, if there is a back-up in the system, the articles begin to bump into each other, creating line pressure, jarring and perhaps damaging each other. In an accumulating conveyor, if there is a back-up in the system, the control system will cause some of the zones to stop driving, creating a "holding pattern" to prevent the articles on the conveyor from bumping into each other. Then, when the back-up is relieved, the zones begin driving again, permitting the articles to flow along the conveyor.
There are several problems with the heavy duty accumulation conveyors that existed prior to the present invention. Pallet accumulation conveyors typically are driven by long strands of chain. They are very noisy and very difficult and expensive to maintain It is a constant struggle to keep the long chains properly tensioned. There are also large power losses in these conveyors, thus wasting energy and limiting the length of conveyor that can be driven with a single drive. Additional drive units must be used in order to drive a long conveyor, and the drive units must be synchronized in some manner to maintain a steady flow of material. This causes considerable additional expense. The noise, waste of energy, difficulty and expense of maintenance, and limitation in length of the conveyor are all serious problems in prior art conveyors.